These are attributes that are available for every HTML element. However, you should note that just because the attribute is available, it does not mean that it will actually do anything.
The accesskey attribute creates a keyboard shortcut to activate or focus on the element:
<element accesskey></element>
The accesskey attribute allows you to create a keyboard shortcut. This can be a space-delimited list of characters. Most browsers on Windows will use Alt + accesskey and most browsers on Mac use Ctrl + Option + accesskey.
Here is an example using a textbox that can be focused on with the character q:
<input type="search" name="q" accesskey="q"/>